<?php
declare(strict_types=1);
function f($x,$y,){
    return 5*$x+3*$y
;}
function f2(int $x, int $y,){
    return $x+$y;
}
echo 'f(3,6)=',f(x:3,y:6),"\n";
echo 'f(3,6)=',f(x:1.2,y:2),"\n";
echo 'f2(3,6)=',f2(x:3,y:6),"\n";
echo 'f2(3.8,6.6)=', @f2((int)3.8,(int)6.6),"\n";